In recent years, the integration degree of semiconductor devices is increasingly improved and the still more minute circuit pattern is requested. Various inspection measures are used for a sample in which circuit pattern is formed as represented by semiconductor wafer for the purpose of quality control and improvement of yield. For example, a scanning electron microscope is known in which a sample is irradiated with a charged particle beam to measure the accuracy of dimensions of circuit pattern or produce an image of the sample from a secondary signal obtained from the sample, so that defect of the circuit pattern or foreign substance attached to the circuit pattern is estimated.
As a line width rule of circuit pattern, the observation magnification having three hundred thousand or more magnifications is sometimes applied in order to conform to the design rule of 35 nm node, for example. The observation view range at this time is equal to or smaller than 0.5 μm on a side. Accordingly, in order to display circuit pattern or defect to be observed in the vicinity of the center of display, it is necessary to recognize sample coordinates with accuracy of one quarter or less of the observation range, for example 0.1 μm. The fixed point observation is sometimes required for specific pattern in all chips formed in wafer for the reason that manufacturing defect is apt to occur or dimensions are required to be managed.
At present, the wafer size is 300 mm in diameter in the mainstream and accordingly a stage of a device on which a wafer is put becomes considerably large. At the same time, a high-output drive mechanism for high-speed operation of stage is required from the viewpoint of improvement of throughput. However, there arises a problem that temperature is increased due to generation of heat in motor and driving shaft of the high-output drive mechanism and the generated heat causes change in temperature of sample or periphery of sample through parts, so that the coordinates of place irradiated with charged particle beam are shifted or deviated from target. Furthermore, when there is temperature difference between wafer and stage, sample is expanded or contracted with time, so that the above problem is caused. Moreover, the irradiated charged particle beam itself is converted into thermal energy to some degree, so that temperature change occurs. For these phenomena, if the observation range is made larger in order to set the coordinates to be observed within the observation range, the coordinates are easily set within the observation range, although there also arises a problem that it is difficult to find small observation object and throughput is reduced. In addition, when the diameter of wafer is increased to 450 mm, it is expected that deviation of coordinates of sample due to temperature change causes large problem.
Heretofore, as a method of reducing thermal expansion of sample or periphery of sample due to the thermal expansion and contraction, there is known a method of measuring temperature of sample and controlling so that the temperature is kept to be fixed by means of heat source such as heater (refer to patent document 1, for example).
Furthermore, there is also known a method of obtaining behavior of sample by temperature change based on energy of charged particle beam with which sample is irradiated in advance by simulation or experiment and correcting deviation of coordinates (refer to patent document 2, for example).